Performance of newer and conventional diagnostic methods in detection of drug sensitive and resistant tuberculous meningitis

Abstract

ObjectiveTo compare the performance of traditional and newer diagnostic methods for diagnosis of tuberculous meningitis (TBM) along with detection of drug resistant TBM. MethodsSingle cerebrospinal fluids sample from 281 suspected TBM patients was processed during August 2011 to July 2012 for acid fast bacilli (AFB) examination by Ziehl-Neelsen and auramine staining methods, AFB culture on Lowenstein-Jensen culture media, by microscope observation of drug susceptibility testing assay, and nucleic acid amplification tests by in-house conventional PCR and in-house real time PCR targeting IS6110 insertion sequence. All the isolates were subjected to drug susceptibility testing for isoniazid, rifampicin, ethambutol and streptomycin by 1% proportion method. ResultsThe percentage positivity by AFB smear examination and culture on Lowenstein-Jensen media was 21% (59/281), 11.4% (32/281) respectively. The detection rate by conventional PCR was 33.1% (93/281). The real time PCR showed positivity rate of 44.8% (126/281). The extra detection by real time PCR was 11.7%. Only one isolate was multiple drug resistant and 22 (68.8%) were pan-susceptible. Remaining eight isolates showed either mono/poly drug resistant to first line antitubercular drugs. ConclusionsReal time PCR is a more sensitive and rapid method if it is appropriately adopted in clinical practice for diagnosis of TBM. Prevalence of multiple drug resistance Mycobacterium tuberculosis causing TBM is low.